Endotracheal tubes are intubated, i.e., inserted into the trachea, to provide a clear passage for air to the lungs if the trachea has been crushed in an automobile accident, for example. Also, a tube may be intubated prior to anesthetizing a patient with a general anesthetic to maintain a clear air passage in case the trachea collapses due to relaxation of the muscles supporting the trachea.
Endotracheal tubes may be intubated through the mouth, designated an oral endotracheal tube; through the nose, designated a nasal endotracheal tube; or through the tracheostomy incision in the front of the neck and trachea, designated a tracheostomy tube. In an emergency situation an oral endotracheal tube is normally used to provide an air passage to the lungs. After the patient's condition has been stabilized, which may require a week or more, the oral endotracheal tube is removed, a tracheostomy incision is made in the neck and trachea, and a tracheostomy tube is intubated through the tracheostomy incision to provide the air passage.
The tubes also may include an inflatable endotracheal balloon or cuff which surrounds and is fixed to the outer surface of the tube adjacent to its lower end. After the tube is inserted into the trachea, the bulb-shaped cuff is inflated with air through a small diameter tube connected to the cuff interior and which runs upward along the tube to the external portion of the tube. The inflated cuff seals the space between the endotracheal tube and tracheal wall, preventing air from escaping from the lungs past the exterior of the tube and preventing saliva and other liquids from draining into the lungs.
The trachea can be stretched and permanently deformed if the cuff is overinflated. Therefore, as the cuff is inflated, passage of air past the cuff is monitored using a stethoscope. When passage of air ceases inflation of the cuff is stopped. The pressure exerted by the cuff against the tracheal wall is sufficient to prevent movement between the cuff and the tracheal wall.
Since the trachea in children is not as pliable as in an adult, an inflated cuff could more easily stretch and permanently deform the trachea of a child. Therefore, pediatric endotracheal tubes do not include inflatable cuffs and the space between the tube and the trachea must be suctioned frequently to deter saliva from collecting in the lungs.
To insure that the tube is not inserted so far that the lower end is within one of the mainstem bronchi causing one of the lungs not to inflate, bilateral chest excursion, i.e., movement of both sides of the chest during breathing, is observed. To verify the location of the lower end of the tube within the trachea, an x-ray opague color strip may be incorporated along the length of the tube. After the tube is inserted into the lumen of the trachea, the cuff is inflated, the tube is anchored in place and proper positioning of the tube is verified by x-ray photography.
The length of the endotracheal portion of the tube, i.e., the amount of tube which is inserted into the patient's trachea, is dependent on the length of the patient's trachea and, in the case of a tracheostomy tube, the location of the tracheostomy incision. The tube should be intubated to the proper depth, namely past the tracheal blockage in the case of a crushed trachea and preferably until the lower or distal end of the tube is within a few centimeters of the bronchial bifurcation of the trachea, i.e., just above the right and left main stem bronchi, whether there is a tracheal blockage or the patient is to be anesthetized. The length of the tube projecting outward from the mouth or neck incision of the patient is dependent on the length of the endotracheal portion.
Once the endotracheal tube, whether an oral tube or a tracheosotmy tube, has been intubated to the proper depth, it must be anchored to the patient to prevent accidental withdrawal of the tube causing possible asphyxiation due to collapse of the trachea and to prevent further insertion of the tube past the bronchial bifurcation. Since the trachea lengthens and contracts as the patient breathes, there will always be some relative movement between the endotracheal tube cuff and the trachea. Such movement causes scar tissue to form which thickens the wall of the trachea. By anchoring the exterior portion of the tube stationarily such movement is minimized.
Since the tubes are made of pliant material and a comatose patient may bite down on an oral endotracheal tube so that the lumen or passage through the tube is constricted, a bite block may be inserted between the upper and lower teeth of the patient when an oral endotracheal tube is used. A typical bite block consists of a relatively hard material which either surrounds the tube or has a thickness approximately equal to the diameter of the tube. Roxburg et. al. U.S. Pat. No. 4,527,559 discloses bite blocks having an elongated hard core which is encapsulated in a block of material not as hard as the core. The block has at least one transverse aperture through which a flexible strip is threaded. The strip is also threaded through a transverse aperture in a specialized endotracheal tube and tied around the patient's neck.
Eross U.S. Pat. No. 3,946,742 discloses a bite block including a retainer having a slotted channel into which an oral endotracheal tube is inserted. The bite block is secured to the endotracheal tube by wrapping an elastic strap which is secured to the bite block around the endotracheal tube and engaging a selected hole in a strap with a post on the bite block. An attachment strap, permanently secured to the bite block, is wrapped around the neck and secured to a post on the bite block. The retainer may be covered with a softer protective layer. The tube is not anchored reliably because the strap around the tube may slip, particularly if it is moistened by saliva, allowing the longitudinal position of the tube within the trachea to change.
Sandstrom U.S. Pat. No. 4,167,946 discloses a bite block having a slotted cylindrical support member into which an endotracheal tube is inserted and a tubular teeth shield member having an internal diameter greater than the external diameter of the endotracheal tube. The bite block also has a radial aperture through which a flexible strip is threaded and used to tie the block to the tube and to the patient. Again the strap when tied around the tube may slip when moistened with saliva.
Sheridan et. al. U.S. Pat. No. 3,973,569 discloses a tracheostomy tube assembly which comprises a tube having a flexible, transversely elongated, fixed flange at the proximal or upper end of the tube; a flexible transversely elongated, slidable flange between the fixed flange and the patient's neck; and a plurality of detachable split rings positioned between the two flanges. As shown in FIG. 3 of the Sherman et. al. reference, the assembly is anchored to the patient's neck by a strap inserted through slots in the outer ends of the fixed and slidable flanges with the slidable flange abutting the patient's neck. By inserting a greater number of split rings between the two flanges, the portion of the tube extending out away from the patient's neck is increased and the endotracheal portion is shortened. The Sheridan et. al. assembly is objectionable because it is complex comprising numerous parts and the range of tube penetration which may be selected is limited to about 3 centimeters.
The tracheostomy tube retainer disclosed in the McGinnis U.S. Pat. No. 3,987,798 surrounds the upper end of the tube and is banded to the patient's neck by a strap extending through slots in the retainer. The retainer includes a pair of opposed struts which project outwardly perpendicular to the patient's neck and have a plurality of slots spaced longitudinally along the struts. The upper or external end of the tube has a pair of opposed lateral tabs which project transversely outward from the tube. Each tab is inserted into a slot in one of the struts to secure the tube to the retainer. The penetration of the McGinnis tracheostomy tube is established by inserting the tabs into the desired slots in the retainer struts. The McGinnis assembly has an undesirably large number of interacting parts. Further the retainer permits only about a 4 cm variation in the endotracheal length and the retainer struts project some 5 cm outwardly from the patient's neck.
The tracheostomy tube assembly of the Ranford et. al. U.S. Pat. No. 4,235,229 includes a tracheostomy tube and a neck collar which has an outstanding deformable sleeve. The collar is strapped around the patient's neck with a tie. The outer end portion of the tube, which has a plurality of ribs, protrudes through the outstanding collar sleeve. A pair of lugs on the outer end of the sleeve projects transversely inward and engages the tube between the ribs to anchor the tube. The range of endotracheal length is limited to about 2.5 cm.
The clamps disclosed in Andrew U.S. Pat. Nos. 3,602,227 and 3,760,811, and Nestor et. al. U.S. Pat. No. 4,249,529 encircle and grip an endotracheal tube. Such clamps are strapped around the neck and/or head of the patient with attachment straps. Since the tube is made of flexible material which becomes slippery when moistened, it may slip relative to the clamp.
In the Schultz U.S. Pat. No. 3,927,676 and Arrott U.S. Pat. No. 3,713,448, oral endotracheal tubes are held with adhesive tape. However, in repositioning and retaping the tube at least daily, repeated stripping of adhesive tape skins the patient's face.
In summary, the tracheostomy tube attachment mechanisms of the prior art are complex, having numerous parts, and the range of selectable endotracheal length is too limited or require special endotracheal tubes. None of the prior art suggests a bite block with a hard core having a portion enclosed in a softer material and an exposed portion to permit securing of the bite block to an endotracheal tube with adhesive tape. Further, none of the prior art suggests a bite block having a hard core with an aperture for attachement of the bite block and tube to a patient.